Heath Lake is located in the county of Berkshire (Figure 1) and was designated as a
Site of Special Scientific Interest (SSSI) in 1989 for its “specialist communities of
native plants and animals...[and] populations of some uncommon and rare aquatic
plant species” (Natural England, 2016). Described as a lowland acid lake with
nutrient poor waters, it has historically been habitat to both aquatic and marginal
plant communities which are more characteristic of upland lakes in Wales, northern
England and Scotland.
The SSSI citation lists alternate water-milfoil (Myriophyllum alterniflorum) to be
growing abundantly, alongside floating club-rush (Eleogiton fluitans), six-stamened
waterwort (Elatine hexandra), blunt-leaved and lesser pondweeds (Potamogeton
obtusifolius and Potamogeton pusillus) and shoreweed (Litorella uniflora). In addition
to this, Coral Necklace (Illecebrum verticillatum), was reported as present at Heath
Lake in Crawley’s 2004 edition of The Flora of Berkshire, and there are records of
Pillwort (Pilularia globulifera) (Porley 1994). The distribution of Coral Necklace is
currently in decline due to increasingly restricted ranges of heathland habitat and has
not been recorded at Heath Lake in recent years.
Heath Lake is currently in unfavourable condition due to nutrient enrichment and
increased base levels of the lake. This has resulted in a significant and rapid change
to the aquatic macrophyte communities both submerged and marginal to the lake